For the following reactions:
$CH_{3}CH_{2}CH_{2}Br + Z^{-} \xrightarrow[substitution]{k_s} CH_{3}CH_{2}CH_{2}Z + Br^{-}$
$CH_{3}CH_{2}CH_{2}Br + Z^{-} \xrightarrow[elimination]{k_e} CH_{3}CH=CH_{2} + HZ + Br^{-}$
where
$Z^{-} = CH_{3}CH_{2}O^{-} (A)$ or $(CH_{3})_{3}CO^{-} (B)$
$k_s$ and $k_e$ are,respectively,the rate constants for the substitution and elimination,and $\mu = \frac{k_s}{k_e}$,the correct option is:

• A
  $\mu_{B} > \mu_{A}$ and $k_e(B) > k_e(A)$
• B
  $\mu_{B} > \mu_{A}$ and $k_e(A) > k_e(B)$
• C
  $\mu_{A} > \mu_{B}$ and $k_e(B) > k_e(A)$
• D
  $\mu_{A} > \mu_{B}$ and $k_e(A) > k_e(B)$